The present invention relates generally to the alignment of visual elements within a conventional head-up display. More specifically, the present invention relates to a method of assigning individual head-up display lens train assembly correction data which further enables ease of interchangeability of the head-up display, enhances viewing accuracy and improves alignment efficiencies.
Ever since the early days of vehicle pioneering, there has always been an inherent danger when an operator of a vehicle, such as a pilot of an aircraft or driver of an automobile, must look down from his outward line of site to view important operative status concerning his vehicle. Such status information is normally presented via analog means such as dials, gauges, or gyroscopes, or digital means such as computer readouts, on a readout display, such as an automobile dashboard or pilot's information panel. The operative status may include information such as fuel, speed, direction, orientation, weapons status, and the like.
As such, when the vehicle operator temporarily looks to the vehicle information display to gather this important information, his outward line of sight is momentarily disrupted. This has inherent dangers, especially in fast moving vehicles such as aircraft and the like. Furthermore, once a vehicle operator is finished gathering the pertinent information, which may take a fraction of a second or sometimes minutes, he must then return to his original line of sight and his focus must readjust. These continual visual diversions relates to problems such as tunnel vision and focus impairment.
It should be noted, however, that the disclosure herein will concentrate on aircraft head-up display devices and enhancements. However, the present invention is applicable to not only aircraft, but also any type of vehicle which may incorporate the usage of a head-up display. As such, the description and emphasis of the present invention's usability within an aircraft should not be deemed limiting, but rather an explanation and exemplification of the present invention.
U.S. Pat. No. 3,205,303, to Bradley, issued on Sep. 7, 1965 ('303 patent) attempts to remedy these problems by inventing a remotely controlled remote viewing system. The '303 patent is one of the first so-called “head-up display” (HUD) units which allows a vehicle operator to receive pertinent vehicle information within his outward line of sight. As such, the vehicle operator does not have to continuously look down to the information display panel to view this information.
There have subsequently been many enhancements and improvements to the '303 patent. For example, U.S. Pat. No. 3,291,906 to Ward et al., issued on Dec. 13, 1996, discloses aircraft visual indicating or display systems utilizing a cathode ray tube;
U.S. Pat. No. 3,666,887, to Freeman, issued on May 30, 1972, discloses a head-up display; U.S. Pat. No. 4,763,990, to Wood, issued on Aug. 16, 1988, discloses a head-up display system; U.S. Pat. No. 5,007,711, to Wood et al., issued on Apr. 16, 1991, discloses a compact arrangement for head-up display components; U.S. Pat. No. 5,805,119, to Erskine et al., issued on Sep. 8, 1998, discloses a vehicle projected display using a deformable mirror device; and U.S. Pat. No. 5,379,132, to Kuwayama et al., issued on Jan. 3, 1995, discloses a display apparatus for a head-up display system.
The HUD has subsequently become an important component of the instrumentation in high performance aircraft of all types, from tactical fighter aircraft to large commercial transports. By projecting into the pilot's view an accurate and properly aligned real-time representation of the aircraft's orientation and environment, the pilot is enabled to control an aircraft more efficiently and effectively through the transition from visual orientation to instrument orientation and back again, while having at all times an accurate representation, either digital, analog or both, of all major flight instruments and weapons systems controls.
However, inherent with the pertinent information that a HUD displays, a clear, accurate, and precise information projection to the pilot is tantamount. Continuous and accurate alignment of the visualization elements within an HUD is imperative in order to make the HUD effective. Visualization errors and distortion cannot be tolerated in these finely tuned assemblies. However, inherent with a HUD's use, constant temperature variations, vibrations, distortion, and initial alignment errors, and the like are omnipresent and methods and processes of combating these problems are continuous.
The main component of any conventional HUD is its optics. The optics is the assembly which conveys and magnifies the information in a viewable display to the pilot. Some HUD assemblies utilize a lens train (assembly of lenses within an optical alignment) of conventional lenses.
Furthermore, because of the previously mentioned need for precise and accurate positioning of information in a HUD, it is thus necessary to correct for distortion of the image caused by the cathode ray tube (CRT) electron beam used in conjunction with the lens train. The form of distortion correction must be able to accommodate both conventional, and most widely used in HUD units, stroke-written display generation (where the CRT electron beam moves to each individual display point to be visualized) and raster display generation (where the CRT electron beam performs a progressive left-right sweep from top to bottom, scanning the entire display anew with each pass).
However, the conventional wave-shaping techniques generating non-linear horizontal and vertical raster sweep signals cannot be used for stroke-written displays. Analog techniques for solving this problem have been devised, and are well known in the field of art. The present invention provides significantly better accuracy than these older analog techniques.
Furthermore, there is a direct need within the aircraft industry to allow components of these HUD systems to be interchangeable. For example, currently if an element of a HUD system fails, it must be replaced and manually realigned on-site. The conventional realignment process is extremely time consuming and very inaccurate. Once a HUD installer believes that the HUD is properly aligned, most distortions and errors subsequently occur during operation of the HUD, such as extreme temperature variations and vibrational loads. As such, it is a back-and-forth process between the pilot and the HUD installer in order to properly perfect the HUD's alignment.
The present invention overcomes the disadvantages and/or shortcomings of known prior HUD alignment and distortion correction methods and apparatus and provides significant improvements thereover.